The present invention is related generally to valve control, and in particular, to valve switching in automatically guided construction equipment.
In construction (e.g., road paving, grading, etc.), conventional systems make ready use of automatic control of certain components of the construction equipment. For example, automatic control may be exerted over valves that actuate certain components on a construction vehicle, such as a grader. Where automatic control is used, systems employ a manual override to allow an operator to control the valves (e.g., raise and/or lower a combine, etc.) in the presence of an obstacle or in other situations that the automatic controller is not configured to handle.
Currently, there are three basic configurations in use for valve control in automated construction equipment. These conventional configurations are depicted in FIGS. 1-3. The arrangement of such systems are well known, so are only described with sufficient detail to highlight the shortcomings of such systems remedied by the present invention. For simplicity of presentation, where analogous components and/or systems are presented in the various prior art configurations of FIGS. 1-3, the analogous components and/or systems are referred to with the same reference numeral—even if not completely identical.
FIG. 1 depicts a conventional valve control system 100. In the prior configuration of FIG. 1, a machine controller 102 drives a valve 104 (e.g., through a valve solenoid, valve controller, etc., not shown) of a hydraulic system 106. Hydraulic system 106 may be a hydraulic system in a construction vehicle as described above and valve 104 may control raising and/or lowering of one or more combines, etc. In automatic operation, machine controller 102 receives automatic control signals from automatic controller 108 via a communication device 110. Communication device 110 is generally a bus, such as a Controller Area Network (CAN) serial bus that utilizes a host controller (not shown) to transmit control signals from the automatic controller to the machine controller. Separately, the machine controller receives control signals (e.g., a current) from a manual controller 112. These control signals are indicative of an operator input at a manual steering command (e.g., steering wheel, steering console, joystick, etc.). When the machine controller 102 receives such control signals from the manual controller 112, the machine controller 102 overrides any control from the automatic controller 108. While conventional valve control system 100 is relatively simple, it is dependent on the performance of machine controller 102. Since the automatic controller 108 and manual controller 112 are connected serially through the machine controller 102 to the valve 104, an automatic control signal may be delayed, leading to deleterious performance.
FIG. 2 depicts a conventional valve control system 200. In the prior configuration of FIG. 2, the automatic controller 108 manipulates control signals from the manual controller 112 at an interface point 202. As in the conventional valve control system 100, since the control signals from the manual controller 112 and the automatic controller 108 (via the interface point 202) are passed serially through the machine controller 102, an automatic control signal may be delayed. Additionally, in such a configuration, there may be issues with steering interference. For example, since steering control signals are passed between the electrical connection of machine controller 102 and manual controller 112, interface point 202 must be physically spliced into this connection, which leads to steering control interference.
FIG. 3 depicts a conventional valve control system 300. In the prior configuration of FIG. 3, an automatic control valve 302 is inserted into hydraulic system 106 in addition to valve 104. The automatic controller 108 drives the automatic control valve 302 while the machine controller 102 drives the valve 104 with manual control input from the manual controller 112. While such a system provides a smooth manual override because the automatic controller 108 and the machine controller 102 are in parallel, conventional valve control system 300 is time consuming and expensive to install and is more prone to failure due to the use of an additional valve.
Therefore, there remains a need to provide an inexpensive way to seamlessly switch between machine control and automatic control with high dynamic response in construction equipment.